March 12, 2008

The functional neuroanatomy of science journalism

There is a particular narrative about science that science journalists love to write about, and Americans love to hear. I call it the 'oppressed underdog' narrative, and it would be great except for the fact that it's usually wrong.

2. X, forever after, became dogma among scientists, simply by virtue of the brilliance and fame of Dr. So-and-so.

3. This dogmatic assent continues unchallenged until an intrepid, underdog scientist comes forward with a dramatic new theory, completely overturning X, in spite of sustained, hostile opposition by the dogmatic scientific establishment.

I agree that this is a great story line, and one that is probably used in situations where it's false more often than in situations where it's true. But the implication that it's a commonly-used narrative is, I think, an example of the frequency illusion.

Unfortunately, there's no search engine that indexes news stories by rhetorical pattern, so it's not easy to compare the relative frequency of such patterns. Thus I have no better evidence for the frequency of my own candidate for Most Pernicious Science Narrative of the Decade:

1. Consider the hypothesis that <Stereotypical-Observation-X-About-People>.
2. Brain Researcher Y used fMRI to show that (some experimental proxy for) X is (somewhat) true. Now we know!
3a. Optional bonus #1: Now we know why! It happens (somewhere) in the brain!
3b: Optional bonus #2: This shows that X is hard-wired and biological, not all soft and socially constructed.

A mother's impulse to love and protect her child appears to be hard-wired into her brain, a new imaging study shows.

Tokyo researchers used functional magnetic resonance imaging (M.R.I.) to study the brain patterns of 13 mothers, each of whom had an infant about 16 months old.

First, the scientists videotaped the babies smiling at their mothers during playtime. Then the women left the room, and the infants were videotaped crying and reaching for their mothers to come back. All of the babies were dressed in the same blue shirt for the video shoot.

M.R.I. scans were taken as each mother watched videos of the babies, including her own, with the sound off. When a woman saw images of her own child smiling or upset, her brain patterns were markedly different than when she watched the other children. There was a particularly pronounced change in brain activity when a mother was shown images of her child in distress.

So let's recap this.

1. Mothers react differently to videos of happy 16-month-olds and crying 16-month-olds.
2. Mother react more strongly to videos of their own 16-month-olds in distress than to videos of other infants in distress.

And guess where in their bodies these differences can be found? In their brains! (Among other places, anyhow.)

It's rhetorically interesting that Ms. Parker-Pope takes the existence of brain differences observed by fMRI as evidence that the reactions in question are "hard-wired", i.e. innate. No doubt the ability to recognize one's children and the impulse to empathize with them have a substantial evolved biological substrate. But the fact that the psychological states in question are distinguishable in fMRI scans tells us nothing whatsoever about the balance between Nature and Nurture, in this case or in any other.

[David Brooks] writes as if demonstrated group differences in brain activity, being "biological", must therefore be innate and essential characteristics of the groups, and not "socially constructed". But how else would socially constructed cognitive differences manifest themselves? In flows of pure spiritual energy, with no effect on neuronal activity, cerebral blood flow, and functional brain imaging techniques?

I guess that it's the bizarre inference from observation in fMRI scans to innateness that makes this story at all newsworthy. If the existence of maternal love been established simply by asking the mothers how they felt ("On a scale from 1 to 7, where ..., how does this video make you feel?"), no one would have published the study or written about it in the newspaper. And other (essentially equivalent) dependent variables would also probably not have rated any notice: judgments of mothers' facial expressions, or other physiological variables such as those that are used in polygraph examinations.

Of course, it's not just the journalists who say silly things about such studies, at least in the popular press:

"This type of knowledge provides the beginnings of a scientific understanding of human maternal behavior," said Dr. John H. Krystal, editor of Biological Psychiatry, which published the study last month. "This knowledge could be helpful some day in developing treatments for the many problems and diseases that may adversely affect the mother-infant relationship."

In fairness to Dr Krystal and the editorial standards of Biological Psychiatry, I thought that I should take a look at the original paper, to see whether it has any real scientific content beyond the "discovery" that mothers recognize their infants, and find their infants' distress distressing, and exhibit measurable differences in brain activity that correspond to these differences in psychological state.

There is indeed some additional information, beyond the fact that the mothers' brains responded variously to the various videos:

We found that a limited number of the mother's brain areas were specifically involved in recognition of the mother's own infant, namely orbitofrontal cortex (OFC), periaqueductal gray, anterior insula, and dorsal and ventrolateral parts of putamen. Additionally, we found the strong and specific mother's brain response for the mother's own infant's distress. The differential neural activation pattern was found in the dorsal region of OFC, caudate nucleus, right inferior frontal gyrus, dorsomedial prefrontal cortex (PFC), anterior cingulate, posterior cingulate, thalamus, substantia nigra, posterior superior temporal sulcus, and PFC.

These results are not without value, I guess, though they are not very specific, and also not in general very surprising.

The researchers did in fact ask the mothers how they felt:

After the fMRI scan, the mother was asked to rate her feelings while viewing sample video clips. The sample video clips consisted of 10 video clips (the mother's own infant and four other infants in each situation), which were selected from the stimuli that had been presented to the mother while in the fMRI scanner. The mother was asked to rate each of 11 descriptors, i.e., happy, motherly, joyful, warm, love, calm, excited, anxious, irritated, worry, and pity, on a five-point scale (−2 = not at all, 0 = neutral, 2 = extremely) while watching each video clip.

Nor is it surprising that Ms. Parker-Pope saw no reason to mention this aspect of the study.

[Note that the rhetorical pattern discussed in this post is a specific example of the general mind-fogging effect of brain-talk, as demonstrated by Deena Skolnick Weisberg ("Distracted by the brain", 6/6/2007).

Note also that some research results of this type are taken to establish the truth of things that are obviously true prior to investigation (in this case, that most mothers can recognize their own infants, and react especially strongly to seeing them in distress), but the same rhetorical technique is sometimes used to establish the "truth" of things that are probably false, e.g. that "men are emotional children".]